1. Field
This document relates to a method for receiving viewing-restricted channel. More specifically, this document relates to a method for receiving broadcast signals of a pay channel in an apparatus not equipped with a function of receiving encoded broadcast signals of a pay channel.
2. Related Art
Various types of digital broadcast receivers such as a set-top box (STB) and a digital television (D-TV) are now in wide use. The set-top box decodes broadcast programs in the form of MPEG data streams received through a broadcast channel into audio and video data and outputs the decoded broadcast programs to a television.
A set-top box equipped with a function of receiving broadcast signals of a viewing-restricted channel (e.g., a pay channel) further comprises a conditional access system (CAS) module and a descrambler. As is well known, a smart card is inserted to the CAS module to be used as a user authentication card for receiving broadcast signals of a pay channel.
Also, the CAS module to which the smart card is inserted generates a control word to be used as a key code for descrambling encoded broadcast streams of a pay channel; the descrambler, by using the control word, carries out a series of operations for descrambling encoded broadcast streams of a pay channel.
Accordingly, the user of a set-top box additionally equipped with the CAS module and the descrambler can watch an encoded broadcast program provided through a pay channel in a normal manner.
Recently, the number of cases is increasing, where people use a main set-top box (STB) equipped with a function of receiving broadcast signals of a pay channel together with one or more sub-STBs not equipped with a function of receiving broadcast signals of the pay channel through a wired or wireless network.